The invention is concerned with a safeguard device having a selective high frequency sensor that triggers an alarm device after receiving high frequency energy.
Safeguard devices of this type containing a sensor reacting to a high frequency field are quite generally known. If this safeguard device comes within a high frequency field, an alarm device is triggered. Safeguard devices of this type are used in department stores to secure high-priced goods from theft. However, it is possible with safeguard devices of this type to prevent the alarm device being triggered by high-frequency-effective shielding. It is sufficient here to pack the safeguard device in aluminum foil or a metal-lined carrier bag or a metal container, for example.